1. Field of the Invention
The present invention relates to a wireless communication apparatus and wireless communication system, and particularly to a technique for reducing the power consumption in a wireless communication apparatus and wireless communication system including a plurality of transmitting portions and/or receiving portions.
2. Description of the Related Art
In recent years, personal computers, portable information terminals, wireless liquid crystal televisions, etc., are widely used, with which the number of wireless LAN (LAN: Local Area Network) systems that form wireless networks for transmitting information are increasing. Currently, as a wireless LAN system standardized by IEEE 802.11, IEEE 802.11b of 2.4 GHz band is prevalent. In addition, IEEE 802.11a of 5 GHz band, which allows communication with higher speed, is also gradually becoming prevalent, with increasing demands on high-speed communication.
Further, as a technique for realizing high-speed wireless communication, there is a transmission method called MIMO (MIMO: Multiple Input Multiple Output). According to this MIMO technique, encoded information to be transmitted is divided into a plurality of data streams, which are then transmitted by a plurality of antennas at the same time and on the same frequency channel. In this manner, a large amount of data can be transmitted on a single frequency channel, thereby supposedly realizing high-speed transmission in wireless communication systems.